The present invention relates to a carrying apparatus for conveying a paper sheet and an image forming apparatus which are comprised, for example, in an electrophotographic copying machine.
In many electrophotographic copying machines, images can be formed on both surfaces of a paper sheet. To form images on both surfaces in this kind of copying machine, a paper sheet is supplied from a paper sheet feed cassette to an image forming section through a paper sheet carrying route (hereinafter simply called ADU), and an image is formed on one surface. The paper sheet on which an image has been formed is then stacked and contained in an intermediate tray. Subsequently, the paper sheet stacked and contained in the intermediate tray is fed again to the image forming section, and an image is then formed on its back surface. Thus, images are formed on both surfaces of a paper sheet which is then fed out onto a sheet discharge tray.
Meanwhile, electrostatic charges have been applied to paper sheets stacked on the intermediate tray, for example, through a transfer process at the image forming section. Therefore, paper sheets easily tend to be fed stuck together due to static electricity, when they are fed again from the intermediate tray.
In addition, since a paper sheet having a surface on which an image has been formed must once be stacked and contained in the intermediate tray, an image cannot be formed sequentially on its back surface. Time loss is therefore caused so that the image forming efficiency is lowered.
To solve the above-described problems that layered paper sheets are fed and the image forming efficiency is lowered, a development has been made in an electrophotographic copying machine which adopts so-called non-stack ADU.
That is, this kind of electrophotographic copying machine carries out continuous image formation on surfaces of a plurality of sheets, excluding the intermediate tray from the ADU. Thereafter, these paper sheets are directly sent to the image forming section, reversed by a reverse carrying means, and an image is formed on the back surface of the paper sheet.
In some cases, the non-stack ADU is used with an accounting device such as a coin controller attached thereto. If data of total 4 pages are double-side-printed on two paper sheets in an electrophotographic copying machine attached with the accounting device, for example, there may be a case that inserted money runs short at the time point when printing on pages 1, 2, and 4 pages.
In this case, the paper sheet on which the third page should be printed should be discharged without carrying out printing or should be kept in the ADU in the apparatus.
Meanwhile, the non-stack ADU is opened/closed in accordance with an operation of opening/closing an open/close door. If a paper sheet jams en route, the open/close door is opened to remove the paper sheet.
However, in a conventional apparatus, the open/close door is kept permanently openable, and there is a case that the door is opened with a paper sheet still in the ADU. In this case, there is a drawback that the paper sheet in the ADU falls drops to the ground and gets dirty.
The present invention has been made in view of the actual situation as described above, and has an object of providing a carrying apparatus and an image forming apparatus in which the carrying route (a reverse carrying route) is inhibited from opening when an object to be carried (an object to which an image should be transferred) is kept on a carrying route (a reverse carrying route).
A carrying apparatus according to the present invention comprises: a carrying device for carrying an object to be carried, along a carrying route; a control device for temporarily stopping and holding the object carried by the carrying device, on the carrying route, if necessary; an open/close door provided in the carrying device, for opening/closing the carrying route; and a limiter device for limiting opening of the open/close door, based on detection of the object by the detection device.
An image forming apparatus according to the present invention comprises: an image forming device for forming an image on an image carrier; a transfer device for transferring the image formed by the image forming device, to an object to which the image should be transferred; a reverse carrying device for carrying the object having a surface to which the image has been transferred, along a reverse carrying route, thereby to reverse and feed the object again to the transfer device, and to transfer an image on another surface of the object; a control device for temporarily stopping and holding the object carried by the reverse carrying device, on the carrying route, if necessary; an open/close door provided in the carrying device, for opening/closing the carrying route; a detection device for detecting the object held on the reverse carrying route; and a limiter device for limiting opening of the open/close door, based on detection of the object by the detection device.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.